The present invention pertains to a tungsten carbide nickel-chromium alloy hard member for use as a wear member, as well for use as a hard insert in a tool. Exemplary wear members include dies, plungers and nozzles. Exemplary tools include point attack style tools (e.g., a road planing tool or a point attack mine tool or an open-face longwall tool) and rotary style tools (e.g., a roof drill bit or a tri-cone bit).
Referring to the hard insert for a point attack style of tool, such point attack style tools have been typically used to penetrate the earth strata or other substrates (e.g., asphalt roadway surfaces) wherein the point attack style tool is carried, either in a rotatable or a non-rotatable fashion, by a driven member (e.g., drum or chain). The typical point attack style tool has had a hard insert affixed at the axially forward end thereof wherein the hard insert has been the part of the point attack style tool which first impinged upon the earth strata or other substrate.
Referring to the hard insert for the rotary style tool for penetrating the earth strata, there are one or more hard inserts at the axially forward end thereof. In the case of a typical roof drill bit, such a rotary tool has been typically used to drill holes in a mine roof. In the case of a tri-cone drill bit, such a rotary tool has been used to drill holes for oil wells and the like. The typical rotary tool has had a hard insert affixed at the axially forward end thereof wherein the hard insert has been the part of the rotary tool which first impinged upon the earth strata or other substrate.
Heretofore, for both the point attack style tool and the rotary style tool the hard insert has comprised a tungsten carbide-based alloy wherein the binder has been cobalt or a cobalt-based alloy. While the tungsten carbide-cobalt hard insert has achieved successful results, there have been some drawbacks to the use of a hard insert made from tungsten carbide and cobalt.
One drawback has been the fact that up to approximately forty-five percent of the world""s primary cobalt production has been from politically unstable regions, i.e., political regions which have in the past decade experienced armed or peaceful revolutions wherein the ruling government has changed very quickly. Thus, there has always remained the potential that the supply of cobalt could be interrupted due to any one of a number of causes. The unavailability of cobalt would, of course, be an undesirable occurrence. Because of the fact that about twenty-six percent of the world""s annual primary cobalt production has been used for the manufacture of superalloys for advanced aircraft turbine engines, cobalt has been designated as a strategic material. These two factors have resulted in cobalt having been relatively expensive, which, in turn, has raised the cost of the hard insert, as well as the cost of the overall point attack style tool. Such an increase in the cost of the point attack style tool has been an undesirable consequence of the use of cobalt in the hard insert.
Wear members (e.g., plungers), point attack style tools, and rotary tools may very well operate in environments which are corrosive. While the tungsten carbide-cobalt materials for use as a wear member or a hard insert have been adequate in such environments, there remains the objective to develop a wear member, as well as a hard insert, which has improved corrosion resistance while maintaining adequate wear characteristics.
It can thus be seen that while the use of tungsten carbide-cobalt wear members and hard inserts have been successful, there remains a need to provide a wear member, as well as a hard insert, which does not have the drawbacks, i.e., cost and the potential for unavailability, inherent with the use of cobalt set forth above. There also remains a need to develop a wear member, as well as a hard insert, for use in corrosive environments which possesses improved corrosion resistance while maintaining adequate wear characteristics.
In one form thereof, the invention is a tool which includes a tool body, and a hard insert affixed to the tool body. The composition of the hard insert comprises from about 5 volume percent to about 40 volume percent binder alloy and between about 60 volume percent and about 95 volume percent tungsten carbide. The tungsten carbide has an average grain size between about 1 micrometer and about 30 micrometers. The binder alloy comprises an alloy of nickel and chromium wherein the nickel ranging between about 70 weight percent and less than 93 weight percent and the chromium ranging between greater than 7 weight percent and about 30 weight percent.
In another form thereof, the invention is a hard insert for use in a rotary tool having a tool body wherein the hard insert is affixed to the tool body. The composition of the hard insert comprises between about 5 volume percent and about 40 volume percent binder alloy, and between about 60 volume percent and about 95 volume percent tungsten carbide. The tungsten carbide has an average grain size between about 1 micrometer and about 30 micrometers. The binder alloy comprises an alloy of nickel and chromium wherein the nickel ranges between about 70 weight percent and less than 93 weight percent and the chromium ranges between greater than 7 weight percent and about 30 weight percent.
In yet another form thereof, the invention is a wear part which comprises between about 5 volume percent and about 40 volume percent binder alloy, and between about 60 volume percent and about 95 volume percent tungsten carbide. The tungsten carbide has an average grain size between about 1 micrometer and about 30 micrometers. The binder alloy comprises an alloy of nickel and chromium wherein the nickel ranges between about 70 weight percent and less than 93 weight percent and the chromium ranges between greater than 7 weight percent and about 30 weight percent.